How to Troubleshoot an 8-Axis Welding Robot?

An 8-axis welding robot combines multi-axis motion, welding equipment, control systems, and workpiece positioning. When a welding problem occurs, the cause may not be the robot arm itself. Incorrect welding parameters, wire feeding problems, fixture positioning, sensor errors, or program settings can also affect the final weld.

A systematic troubleshooting process helps identify the source of the problem without unnecessarily replacing components.

1. Start With the Robot Alarm

When an 8-axis welding robot stops unexpectedly, check the controller and alarm display first.

Record the alarm code and determine whether it is related to:

Servo or motor errors

Axis overtravel

Positioning errors

Communication faults

Safety circuit activation

Welding power source

Wire feeding system

Sensor or external equipment

Do not reset the system repeatedly without identifying the cause. The alarm history can provide useful information about what happened immediately before the stoppage.

2. Check Each Axis for Abnormal Movement

An 8-axis system has multiple coordinated movement axes. If the robot cannot reach a programmed position, moves unexpectedly, or produces positioning errors, check whether any axis is approaching its mechanical or software travel limit.

Inspect:

Axis position

Servo status

Mechanical obstruction

Cable interference

Abnormal noise or vibration

Zero or reference position

Robot-to-fixture clearance

If the problem occurs only at a specific position, check the welding program and workpiece fixture before assuming that the robot hardware has failed.

3. Inspect the Welding Torch Position

Poor weld quality does not necessarily indicate a problem with the welding power source.

An incorrect torch position can change the welding angle, arc length, and distance from the joint.

Check:

Torch angle

Contact-tip-to-work distance

Torch alignment

Torch collision or deformation

TCP (Tool Center Point) settings

Welding path

If the robot repeatedly produces the same weld deviation, verify the programmed TCP and calibration.

4. Check Wire Feeding Problems

Wire feeding problems are common causes of unstable arc welding.

If the wire does not feed smoothly, inspect the complete wire feeding path:

Welding wire spool

Wire feeder

Drive rolls

Wire liner

Contact tip

Welding torch

Look for excessive resistance, contamination, worn components, incorrect drive-roll selection, or an improperly installed liner.

Symptoms such as irregular wire feeding, arc instability, or frequent burnback may originate from the feeding system rather than the robot axes.

5. Check Welding Parameters

If the robot moves normally but the weld is poor, verify the welding parameters.

Important settings include:

Welding current

Welding voltage

Wire feed speed

Travel speed

Shielding gas flow

Welding mode

Torch angle

Compare the actual parameters with the qualified welding procedure or the parameters established for the specific material and joint.

Changing several parameters at once can make troubleshooting more difficult. Adjust one variable at a time whenever practical.

6. Check Shielding Gas

Porosity and unstable weld appearance can result from inadequate shielding gas.

Check the gas cylinder or supply system, regulator, hoses, valves, and torch nozzle.

Also inspect the nozzle for excessive spatter accumulation. A partially blocked nozzle can interfere with shielding around the welding arc.

If gas flow appears normal but porosity continues, inspect the welding environment for drafts and check whether the workpiece surface has contamination, moisture, oil, or other substances that may affect weld quality.

7. Verify Workpiece and Fixture Positioning

An 8-axis welding robot follows its programmed path based on the expected position of the workpiece.

If the fixture shifts or the component is loaded incorrectly, the robot may follow the correct program but still weld the wrong location.

Check:

Fixture clamping

Workpiece orientation

Locating pins

Fixture wear

Part dimensions

Fixture-to-robot alignment

For repetitive production, consistent fixture positioning is particularly important because even a small positioning error can be repeated across a large batch.

8. Check the Welding Program

If the welding robot works correctly on one product but produces errors on another, inspect the corresponding program.

Check for:

Incorrect program selection

Incorrect welding sequence

Wrong coordinate system

Incorrect TCP

Incorrect workpiece coordinate

Incorrect speed

Missing welding points

Incorrect axis synchronization

For an 8-axis system, also verify that the additional axis or positioning mechanism is correctly synchronized with the robot movement.

9. What If the Robot Produces a Collision Alarm?

If a collision occurs, stop operation and inspect the torch, workpiece, fixture, and robot path before restarting.

Do not simply clear the collision alarm and resume production.

Check whether:

The workpiece was incorrectly positioned

The fixture has moved

A welding component has deformed

The programmed path is incorrect

A previous collision changed torch alignment

An axis has lost its reference position

After a collision, torch calibration and robot positioning should be verified before returning to normal production.

10. Troubleshooting Guide

When Should Professional Service Be Required?

Operators can usually perform basic inspections such as checking alarms, wire feeding, gas supply, fixture positioning, and welding parameters.

However, qualified service personnel should be involved when troubleshooting involves:

Servo drive faults

Controller hardware

Encoder problems

Electrical wiring

Safety circuits

Repeated collision errors

Axis calibration

Internal welding power-source faults

Attempting to repair electrical or servo components without appropriate training can create additional equipment and safety risks.

Preventing Recurring Problems

Troubleshooting should not stop after the robot returns to operation. If the same fault occurs repeatedly, identify the underlying cause.

A preventive maintenance program should include regular inspection of the robot axes, torch, wire feeder, cables, fixtures, sensors, and welding equipment.

Operators should also record recurring alarms, maintenance activities, component replacements, and welding defects. This creates a useful maintenance history and makes future troubleshooting faster.

Conclusion

Troubleshooting an 8-axis welding robot requires checking the complete welding system rather than focusing only on the robot arm. Start with the alarm information, then inspect axis movement, torch positioning, wire feeding, welding parameters, shielding gas, fixtures, and program settings.

For repeated problems, calibration, maintenance records, and professional technical support can help determine whether the issue originates from the robot, welding equipment, fixture, or production process.

Juyoubao provides multi-axis robotic welding solutions and can configure welding systems according to workpiece geometry, welding requirements, production volume, and automation needs.